Transconnector for coupling spinal rods

ABSTRACT

The present invention is directed to a transconnector for coupling first and second spinal fixation rods or other elongate fixation elements. The transconnector includes a male member, a female member, and a locking member. The male member has a body with a linking element (such as a hook) associated with the lateral end for receiving one of the fixation elements, and a projection on the medial end. The projection includes a recess defined by lateral and medial walls. The female member has a body with a linking element associated with the lateral end for receiving the other fixation element, and a cavity with an opening on the medial end for receiving a portion of the male member projection. The locking member secures the position and orientation of the male member projection portion in the cavity in order to accommodate different separation distances and orientations between the first and second fixation elements. The locking member cooperates with the medial wall of the recess of the projection to prevent uncoupling of the male and female members. The male member may be made as a two component assembly in which the two components can rotate relative to one another for accommodating rod convergence or divergence.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 09/927,350, filed Aug. 13, 2001 now U.S. Pat. No. 6,736,817 B1,which is a continuation of U.S. patent application Ser. No. 09/466,725,filed Dec. 17, 1999, now U.S. Pat. No. 6,283,967 B1, the entire contentof which are expressly incorporated herein by reference thereto.

FIELD OF THE INVENTION

The present invention relates to a device for spinal fixation, and inparticular to a transconnector for coupling spinal rods, plates, orother elongate members.

BACKGROUND OF THE INVENTION

It is often necessary to surgically treat spinal disorders such asscoliosis. Numerous systems for use in spinal correction and fixationhave been disclosed. These systems usually include a pair of elongatemembers, typically either rods or plates, placed along the vertebralcolumn. For the sake of simplicity, the term “rod” is used throughout torefer to any elongate member. Each rod is attached to the spine withvarious attachment devices. These attachment devices may include, butare not limited to, pedicle screws, plates, transverse process hooks,sublaminar hooks, pedicle hooks, and other similar devices.

It is also well known that the strength and stability of the dual rodassembly can be increased by coupling the two rods with a cross-brace ortransconnector which extends substantially horizontal to thelongitudinal axes of the rods across the spine. The simplest situationin which a transconnector could be used occurs when the two rods aregeometrically aligned. Specifically, the two rods are parallel to eachother, i.e. there is no rod convergence or divergence in themedial-lateral direction; the two rods have the same orientation withrespect to the coronal plane (viewed in the anterior-posteriordirection), i.e. the rods are coplanar from a lateral view; and the tworods are located a uniform distance from each other.

Due to a wide variety of factors, the two rods are rarely threedimensionally geometrically aligned in clinical situations. There areseveral ways to address the variations of geometrical alignment. First,one or both of the rods can be bent to accommodate the transconnector.However, any bending in either of the rods can adversely affect thefixation to the spine and comprise clinical outcome. Furthermore, thebending can also adversely affect the mechanical properties of the rods.The transconnector can also be bent so that the disturbance to the rodpositioning is minimized. As is the case with bending of the rods, themechanical properties of the transconnector could be compromised.

Transconnectors with some adjustability have been designed to adapt forvariations from geometrical alignment. However, most are multi-piecesystems that can be difficult to assemble and use in the surgicalenvironment. U.S. Pat. No. 5,980,523 discloses a multi-piece transverseconnector for spinal rods that can accommodate converging or divergingrods. However, accidental disassembly of the connector by the surgeon ispossible. Even those that are one-piece designs do not allow foradjustments to compensate for all three modes in which there may bevariation from geometrical alignment: convergence or divergence,non-coplanar rods, and variability in rod separation distances. Forexample, U.S. Pat. No. 5,947,966 discloses a device for linking adjacentspinal rods. In one embodiment, the device includes two members that aremovable with respect to one another to accommodate different rodseparation distances. A pin on one member engages a groove on the othermember to provisionally couple the two members, thereby preventing asurgeon from separating the two members. Because the pin is sized toexactly fit the groove, no movement of the pin transverse to thelongitudinal axis of the groove is possible. As a result, the devicedisclosed in the '966 patent cannot accommodate non-coplanar rods oradjust for rod convergence or divergence.

Thus, there exists a need for an improved transconnector for couplingspinal rods.

SUMMARY OF THE INVENTION

The present invention relates to a transconnector for coupling first andsecond elongate spinal fixation elements that have different threedimensional orientations. The transconnector includes a male member, afemale member and a locking member and can be made of any suitablematerial such as titanium, a titanium alloy, or stainless steel. Themale member comprises a body with lateral and medial ends, a linkingelement associated with the lateral end and being configured anddimensioned to receive one of the fixation elements, and a projection onthe medial end. The projection includes a body with a recess defined bylateral and medial walls. The female member comprises a body withlateral and medial ends, a linking element associated with the lateralend and being configured and dimensioned to receive one of the fixationelements, and a cavity with an opening on the medial end which isconfigured and dimensioned to receive a portion of the male memberprojection. The locking member secures the position and orientation ofthe male member projection portion in the cavity in order to accommodatedifferent separation distances and orientations between the first andsecond fixation elements. The locking member interacts with the medialwall of the recess to limit travel of the male member projection portionin the cavity, thereby preventing uncoupling of the male and femalemembers.

Preferably, the locking member comprises a threaded hole in the body ofthe female member and a set screw threadably received in the threadedhole. The set screw has a first end for receiving a tool to turn the setscrew and a second end contactable with the projection for pressing theprojection against the cavity. The recess may have a width wider than awidth of the second end of the set screw for the rotation of theprojection in the cavity. In an exemplary embodiment, the projection hasa substantially cylindrical shape with a first radius and the recess hasa curved upper surface with a second radius. The first radius is largerthan the second radius and the second end of the set screw extends intothe recess to limit the rotation of the projection in the cavity. Theset screw can be a threaded cylindrical body transitioning to a tip atthe second end of the set screw.

The male member body may comprise a link terminal having a lateral endwith the male member linking element, an intermediate link having amedial end with the projection of the male member and a lateral endengaging the medial end of the link terminal, and a locking element forsecuring the link terminal to the intermediate link. Preferably, themedial end of the link terminal includes a first textured surface andthe lateral end of the intermediate link includes a second texturedsurface mating with the first textured surface. The first texturedsurface is rotatable with respect to the second textured surface foraccommodating convergence or divergence between the first and secondrods. An example of suitable first and second textured surfaces includesa radial or star-grind pattern.

The locking element preferably comprises a first hole through the medialend of the link terminal, a second hole through the lateral end of theintermediate link aligned with the first hole, and a cap screwinsertable in the first and second holes. The cap screw may have asecond end with a retaining ring for preventing removal of the cap screwfrom the second hole. The retaining ring may include a resilient memberwhich flexes inward upon insertion of the cap screw through the secondhole and flexes outward once the resilient member is past a collar inthe second hole. Preferably, the resilient member includes an end of thecap screw with a lip and a plurality of slits.

If rods are used for the elongate fixation elements, then the malemember linking element preferably comprises a hook and the female memberlinking element preferably comprises a hook. The lateral ends of themale and female members each may include a threaded hole and a clampingscrew threadably received in the respective threaded hole for securingthe fixation elements to the respective hook. The fixation elements arepreferably clamped between a conical second body portion of therespective clamping screw and a region near the tip portion of therespective hook when the transconnector is secured to the fixationelements.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention are disclosed in theaccompanying drawings, wherein similar reference characters denotesimilar elements throughout the several views, and wherein:

FIG. 1 shows a top perspective view of a transconnector according to thepresent invention with an elongate fixation element attached at eachend;

FIG. 2 shows a bottom perspective view of the transconnector without thefixation elements;

FIG. 3 shows a cross-sectional view of the transconnector with onefixation element attached;

FIG. 4 shows a perspective view of a portion of one embodiment of themale member;

FIG. 5 shows a cross-section of the male member taken through line 5—5of FIG. 4;

FIG. 6 shows a perspective view of the female member of thetransconnector;

FIG. 7 shows a side view of the female member;

FIG. 8 shows a side view of a link terminal of the male member with apartial cross section;

FIG. 9 shows a cross-sectional view of an intermediate link of the malemember;

FIG. 9 a shows a plan view of a textured surface of the link terminaland a textured surface of the intermediate link; and

FIG. 10 shows a perspective view of a cap screw used to join the linkterminal and intermediate link.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a transconnector 10 according to the present invention forcoupling a first elongate spinal fixation element 12 to a secondelongate spinal fixation element 14. Transconnector 10 can be made ofany suitable material typically used in orthopaedic applications such astitanium, titanium alloy, or stainless steel. If transconnector 10 ismade of a metallic material, preferably it is the same metallic materialused for fixation elements 12, 14 to avoid galvanic (mixed-metal)corrosion. First and second fixation elements 12, 14 can be cylindricalrods, rectangular bars, plates, or any other device suitable for spinalfusion. In use, first fixation element 12 extends along one side of thevertebral column and second fixation element 14 extends along the otherside of the vertebral column. A wide variety of attachment devices suchas hooks, screws, and clamps, can be used to attach first and secondfixation elements 12, 14 to the spine.

Transconnector 10 includes a male member 16, a female member 18, and alocking member 20. Male member 16 has a body with a linking element 22on the lateral end for receiving first fixation element 12 and aprojection 24 extending from the medial end of the body. Female member18 has a body with a linking element 26 on the lateral end for receivingsecond fixation element 14 and a cavity 28 with an opening 30 (FIGS. 6and 7) on the medial end of the body for receiving a portion ofprojection 24. Locking member 20 secures the portion of projection 24 incavity 28. The portion of projection 24 received in cavity 28 isadjustable for accommodating different separation distances d betweenfirst and second fixation elements 12, 14. This feature allowstransconnector 10 to be readily adjusted for different patient anatomiesand used in different regions of the spine. For example, the lumbarvertebrae are typically larger than the thoracic vertebrae. As a result,the distance between fixation elements in the lumbar region would begreater than fixation elements in the thoracic region. Because thelength of projection that slides into cavity 28 can be varied,transconnector can be adjusted for use in different spinal regionswithout the need to bend either fixation rods or transconnector 10. Inorder to further increase the adjustability of transconnector 10, femalemember 18, cavity 28, and projection 24 can be manufactured in differentsizes.

Projection 24 is rotatable in cavity 28 for accommodating differencesbetween the angular orientation of first fixation element 12 withrespect to the coronal plane and the angular orientation of secondfixation element 14 with respect to the coronal plane. Specifically,first fixation element 12 has a longitudinal axis L₁ which runs at anangle ÿ₁ with respect to Line AP₁, which is perpendicular to plane C,and second fixation element 14 has a longitudinal axis L₂ which runs atan angle ÿ₂ with respect to Line AP₂, which is also perpendicular toplane C, a plane which divides the body in half from front to back.Because projection 24 can rotate in cavity 28, transconnector can beused in situations in which ÿ₁ differs from ÿ₂ without the need to bendeither fixation element or transconnector 10.

As seen best in FIGS. 3, 4, and 5, projection 24 has a substantiallycylindrical-like shape and includes a recess 32 defined by lateral andmedial walls 34, 36. As will be described in more detail below, medialwall 36 of recess 32 forms a stop against locking member 20 to limittravel of projection 24 in cavity 28, thereby preventing uncoupling ofmale member 16 and female member 18. Recess 32 can be formed having anumber of different configurations (e.g. a flat planar surface) so longas medial wall 36 contacts locking member 20 before projection 24 iscompletely removed from cavity 28 and projection 24 can rotate withincavity 28. FIGS. 4, 5, and 9 show an exemplary embodiment of recess 32.A portion of an upper surface of recess 32, defined by angle ÿ, has areduced radius r₂ compared to the radius r₁ outside of the area definedby angle ÿ. Arcuate surfaces 38 serve as a transition region fromreduced radius r₂ to radius r₁. Radius r₂ and arcuate surfaces 38 can bemanufactured using a number of different techniques. For example, theycan be machined out by cutting, ball milling, or other millingprocesses.

As previously noted, locking member 20 secures the portion of projection24 in cavity 28. FIGS. 1, 3, 6, and 7 show that locking member 20includes a threaded hole 42 in female member 18 and a set screw 44. Setscrew 44 threads into threaded hole 42 and a second end 46 pressesprojection 24 to clamp it against the walls of cavity 28. In anexemplary embodiment, set screw 44 comprises a threaded cylindrical body47 that transitions to a tip at second end 46. A first end 48 of setscrew 44 has an appropriately shaped and sized hole 50 (or a slot) forreceiving a surgical instrument like a screwdriver to turn set screw 44.

As also previously noted, projection 24 can rotate in cavity 28 toaccommodate different orientations of first and second fixationselements 12, 14. The degree of possible rotation is determined by thegeometries of recess 32 and set screw 44. Specifically, projection 24can rotate within recess 32 until set screw 44 engages the edges ofrecess 32. With respect to the embodiment shown in FIGS. 4 and 5, angleÿ, which includes the area of angle ÿ and arcuate surfaces 38, definesthe amount of rotation of projection 24 that is possible until secondend 46 of set screw 44 engages the edges of recess 32 (that has thelarger radius r₁).

In summary, recess 32 and locking member 20 interact to permitaccommodation of non-coplanar rods and variability in rod separationdistances. When locking member 20 includes set screw 44, set screw 44can be in two basic positions. In the clamped position, set screw 44 isthreaded into threaded hole 42 so that second end 46 presses againstrecess 32 to clamp projection 24 against the walls of cavity 28. In theun-clamped position, movement of projection 24 within cavity 28 ispermitted. The range of movement is limited by contact between set screw44 and the boundaries of recess 32. In one embodiment, set screw 44 canbe completely removed from threaded hole 42, thereby allowing projection24 to completely leave cavity 28 and complete uncoupling of male andfemale members 16, 18. In another embodiment, set screw 44 is “staked”so that set screw 44 can not come out of threaded hole 42 without anincrease in torque. One way to achieve this is by mechanically deformingthe first threads of threaded hole 42 so that set screw 44 cannot beunscrewed past the damaged threads. It should also be noted thatdepending on the relative geometries of the set screw 44 and medial wall36, uncoupling of male and female members 16, 18 may still be possibleeven without complete removal of set screw 44 from threaded hole 42regardless of whether set screw 44 is staked.

FIGS. 1, 8, and 9 show an exemplary embodiment of the body of malemember 16 as a two piece assembly which includes a link terminal 52, anintermediate link 54, and a locking element 56 to secure the twotogether. A lateral end of link terminal 52 has male member linkingelement 22 and intermediate link 54 has a medial end with projection 24and a lateral end 58 which engages a medial end 60 of link terminal 52.Medial end 60 of link terminal 52 includes a first textured surface 62which mates with a second textured surface 64 of lateral end 58 ofintermediate link 54 in such a fashion that first textured surface 62 isrotatable with respect to second textured surface 64 to accommodate forany convergence or divergence between first and second fixation elements12, 14. First and second textured surfaces 62, 64 are provided with aplurality of teeth, such as a radial or star-grind pattern, in order tohelp maintain link terminal 52 at the desired angular orientation.Locking element 56 includes a first hole 66 through medial end 60 oflink terminal 52 and a second hole 68 through lateral end 58. First andsecond holes 66, 68 align so that a cap screw 70 can be insertedtherethrough.

Referring to FIGS. 8–10, cap screw 70 has a first end 72 with a slot 74for receiving a tool to turn cap screw 70 and a second end 76 with aretaining ring 78 for preventing removal of cap screw 70 from first andsecond holes 66, 68. Retaining ring 78 has slits 80 which allowretaining ring to flex inward to be inserted through a collar 82 insecond hole 68. Once retaining ring 78 is inserted past collar 82,retaining ring 78 flexes back outward so that cap screw 70 can not becompletely screwed out of first and second holes 66, 68. A body 84 ofcap screw 70 is provided with threads 86 which engage threads 88 on thewalls of second hole 68.

The structure of linking elements 22, 26 will depend on the structure offixation elements 12, 14. For example, if fixation rods 12, 14 areelongate plates, then linking elements 22, 26 are configured anddimensioned to receive elongate plates. Such configurations andconfigurations for other types of fixation elements are well known inthe art. If fixation elements 12, 14 are cylindrical rods as shown inthe drawings, then linking elements 22, 26 each comprises a hook 90. Thelateral ends of male and female members 16, 18 each includes a threadedhole 92 and a clamping screw 94 threadably received in threaded hole 92for securing first and second fixation elements 12, 14 to hook 90.

As seen best in FIGS. 2 and 3, each clamping screw 94 has a first end 96with a slot 98 for receiving a tool to turn clamping screw 94, athreaded cylindrical first body portion 100, and a conical second bodyportion 102. Each hook 90 comprises a tip portion 104 and a curvedportion 106. Curved portion 106 has a radius of curvature larger thanthe radius r of fixation elements 12, 14. As a result, the only contactbetween hooks 90 and fixation elements 12, 14 is at a region near tipportion 104. Furthermore, the only contact between clamping screws 94and fixation elements 12, 14 is on conical second body portion 102.Thus, fixation elements 12, 14 is clamped between conical second bodyportion 102 and the region near tip portion 104.

While various descriptions of the present invention are described above,it should be understood that the various features can be used singly orin any combination thereof. Therefore, this invention is not to belimited to only the specifically preferred embodiments depicted herein.

Further, it should be understood that variations and modificationswithin the spirit and scope of the invention may occur to those skilledin the art to which the invention pertains. Accordingly, all expedientmodifications readily attainable by one versed in the art from thedisclosure set forth herein that are within the scope and spirit of thepresent invention are to be included as further embodiments of thepresent invention. The scope of the present invention is accordinglydefined as set forth in the appended claims.

1. A transconnector for coupling first and second longitudinal spinalrods, the transconnector comprising: a first member having a first hookportion sized and configured to engage the first longitudinal spinal rodand a projection associated with the first hook portion, the first hookportion having a through hole therein, and the projection having anaperture, the first member further comprising a shaft member extendingthrough both the through hole and the aperture forming an axis ofrotation about which the first hook portion can articulate with respectto the projection; a second member having a second hook portion sizedand configured to engage the second longitudinal spinal rod and a cavityhaving at least one opening sized and configured to receive at least aportion of the projection; and a locking assembly for securing differentseparation distances and angular orientation between the first andsecond members, the locking assembly having a first end accessible by auser to rotate at least a portion of the locking assembly to prevent atleast one of the translational or rotational movement of the firstmember with respect to the second member; wherein the locking assemblyhas at least a first position permitting the first member to slide androtate with respect to the second member, with the first hook portion ofthe first member at a user selected angle relative to the second hookportion, and at least a second position preventing at least one oftranslational or rotational movement of the first member with respect tothe second member.
 2. The transconnector of claim 1 wherein rotation ofthe first end of the locking assembly presses the projection against thecavity.
 3. The transconnector of claim 1 wherein a second end of thelocking assembly directly or indirectly engages the projection toprevent movement of the first member with respect to the second member.4. The transconnector of claim 1 wherein the locking assembly consistsof a single screw.
 5. The transconnector of claim 1 wherein the lockingassembly is operatively associated with the projection to limit travelof the first member to prevent uncoupling of the first and secondmembers.
 6. The transconnector of claim 1 wherein the projection is anelongated member having an arcuate section with a relatively flat topsurface and the flat top surface includes a medial wall.
 7. Thetransconnector of claim 6 wherein the projection further includes sideedges at respective junctures of the flat top surface and the arcuatesection.
 8. The transconnector of claim 7 wherein interaction of thelocking assembly and the medial wall prevents uncoupling of the firstand second members.
 9. The transconnector of claim 8 wherein the sideedges limit rotation of the projection in the cavity.
 10. Thetransconnector of claim 9 wherein interaction of the locking assemblywith the side edges limits rotation of the projection in the cavity. 11.The transconnector of claim 1 wherein the shaft member comprises athreaded screw.
 12. The transconnector of claim 11 wherein the shaftmember is adjustable to lock the hook portion of the first member withrespect to the projection.
 13. The transconnector of claim 1 wherein theprojection comprises an edge formed by the junction between the arcuateportion and the flat surface, the edge and the cavity being sized andconfigured to limit angulation of the first member with respect to thesecond member.
 14. The transconnector of claim 1 wherein at least aportion of the projection limits angulation of the first member withrespect to the second member.
 15. The transconnector of claim 1 whereinthe locking assembly in the second position prevents both translationaland rotational movement of the first member within respect to the secondmember.
 16. The transconnector of claim 1 wherein the second member hasa threaded opening sized and configured to threadedly receive thelocking assembly.
 17. The transconnector of claim 16 wherein the lockingassembly comprises a set screw that directly or indirectly engages theprojection to substantially prevent movement of the first member withrespect to the second member.
 18. The transconnector of claim 17 whereinthe threaded opening has a central axis, the central axis issubstantially perpendicular to the projection.
 19. The transconnector ofclaim 1 wherein the cavity is integrally formed with the hook portion ofthe second member.
 20. The transconnector of claim 1 wherein the firsthook portion of the first member is integrally formed with theprojection.
 21. A transconnector for coupling first and secondlongitudinal spinal rods, the transconnector comprising: a first memberhaving a first hook portion sized and configured to engage the firstlongitudinal spinal rod and a projection associated with the first hookportion, the first member comprising: a first body portion having alateral end incorporating the first hook portion and a medial end; asecond body portion having a medial end incorporating the projection anda lateral end engaging the medial end of the first body portion; and alocking element for securing the first body portion with respect to thesecond body portion; a second member having a second hook portion sizedand configured to engage the second longitudinal spinal rod and a cavityhaving at least one opening sized and configured to receive at least aportion of the projection; and a locking assembly for securing differentseparation distances and angular orientation between the first andsecond members, the locking assembly having a first end accessible by auser to rotate at least a portion of the locking assembly to prevent atleast one of the translational or rotational movement of the firstmember with respect to the second member; wherein the locking assemblyhas at least a first position permitting the first member to slide androtate with respect to the second member, with the first hook portion ofthe first member at a user selected angle relative to the second hookportion, and at least a second position preventing at least one oftranslational or rotational movement of the first member with respect tothe second member.
 22. The transconnector of claim 21 wherein the medialend of the first body portion includes a first textured surface; thelateral end of the second body portion includes a second texturedsurface mating with the first textured surface; and the first texturedsurface is rotatable with respect to the second textured surface foraccommodating convergence or divergence between the first and secondmembers.
 23. The transconnector of claim 22 wherein the first and secondtextured surfaces include a star-grind pattern.
 24. The transconnectorof claim 23 wherein the locking element comprises: a first hole throughthe medial end of the first body portion; a second hole through thelateral end of the second body portion aligned with the first hole; anda cap screw insertable in the first and second holes.
 25. Thetransconnector of claim 24 wherein the cap screw has a first end forreceiving a tool to turn the cap screw and a second end with a retainingring for preventing removal of the cap screw from the second hole. 26.The transconnector of claim 25 wherein the cap screw has a body withthreads and the second hole is threaded for threadably receiving the capscrew.
 27. The transconnector of claim 26 wherein the second holeincludes a collar and the retaining ring includes a resilient member,the resilient member flexing inward upon insertion of the cap screwthrough the second hole and flexing outward once the resilient member ispast the collar for preventing removal of the cap screw.
 28. Thetransconnector of claim 27 wherein the resilient member includes an endof the cap screw with a lip and a plurality of slits.
 29. Thetransconnector of claim 1 wherein the first hook portion of the firstmember and the second hook portion of the second member each includes athreaded hole and a clamping screw threadably received in the respectivethreaded hole for securing the first and second longitudinal spinal rodsto the first and second members, respectively.
 30. The transconnector ofclaim 29 wherein each clamping screw has a first end for receiving atool to turn the clamping screw, a threaded cylindrical first bodyportion, and a conical second body portion.
 31. The transconnector ofclaim 30 wherein the first hook portion of the first member and thesecond hook portion of the second member each comprises a tip portionand a curved portion having a radius of curvature larger than that ofthe first and second spinal longitudinal spinal rods, respectively. 32.The transconnector of claim 31 wherein the first and second longitudinalspinal rods are clamped between the conical second body portion of eachclamping screw and a region near the tip portion of the first and secondhook portion, respectively.
 33. A transconnector for coupling first andsecond elongate spinal fixation elements, the transconnector comprising:a first member having a first linking portion configured and dimensionedto receive at least one of the elongate spinal fixation elements, and aprojection associated with the first linking portion, the first linkingportion having a through hole therein, and the projection having anaperture, the first member further comprising a shaft member extendingthrough both the through hole and the aperture forming an axis ofrotation about which the first linking portion can articulate withrespect to the projection; a second member having a second linkingportion configured and dimensioned to receive at least one of theelongate spinal fixation elements, and a cavity having at least oneopening to receive at least a portion of the projection; and a lockingassembly for securing different separation distances between the firstand second fixation elements, the locking assembly having a first endaccessible by a user to rotate at least a portion of the lockingassembly to limit translational travel of the first member with respectto the second member, wherein the locking assembly has at least a firstposition permitting the first member to slide with respect to the secondmember, with the first linking portion of the first member at a userselected angle relative to the second linking portion of the secondmember, and at least a second position preventing translational movementof the first member with respect to the second member.
 34. Thetransconnector of claim 33 wherein rotation of the first end of thelocking assembly presses the projection against the cavity.
 35. Thetransconnector of claim 33 wherein a second end of the locking assemblydirectly or indirectly engages the projection to prevent movement of thefirst member with respect to the second member.
 36. The transconnectorof claim 33 wherein the locking assembly consists of a single screw. 37.The transconnector of claim 33 wherein the locking assembly isoperatively associated with the projection to limit travel of the firstmember to prevent uncoupling of the first and second members.
 38. Thetransconnector of claim 33 wherein the projection has an arcuate portionwith a relatively flat planar surface defining edges at the juncture ofthe flat planar surface and the arcuate portion and the flat planarsurface includes a medial wall.
 39. The transconnector of claim 38wherein interaction of the locking assembly and the medial wall preventsuncoupling of the first and second members.
 40. The transconnector ofclaim 39 wherein the edges limit rotation of the projection in thecavity.
 41. The transconnector of claim 40 wherein interaction of thelocking assembly with the side edges limits rotation of the projectionin the cavity.
 42. The transconnector of claim 33 wherein the shaftmember comprises a threaded screw.
 43. The transconnector of claim 42wherein the shaft member is adjustable to lock the first linking portionof the first member with respect to the projection.
 44. Thetransconnector of claim 33 wherein the edges and the cavity are sizedand configured to limit angulation of the first member with respect tothe second member.
 45. The transconnector of claim 33 wherein at least aportion of the projection limits angulation of the first member withrespect to the second member.
 46. The transconnector of claim 33 whereinthe second member has a threaded opening sized and configured tothreadedly receive the locking assembly.
 47. The transconnector of claim46 wherein the locking assembly comprises a set screw that directly orindirectly engages the projection to substantially prevent movement ofthe first member with respect to the second member.
 48. Thetransconnector of claim 47 wherein the threaded opening has a centralaxis, the central axis is substantially perpendicular to the projection.49. The transconnector of claim 33 wherein the cavity is integrallyformed with the second linking portion of the second member.
 50. Thetransconnector of claim 33 wherein the first linking portion of thefirst member is integrally formed with the projection.
 51. Atransconnector for coupling first and second elongate spinal fixationelements, the transconnector comprising: a first member having a firstlinking portion configured and dimensioned to receive at least one ofthe elongate spinal fixation elements, and a projection associated withthe first linking portion, the first member comprising: a first bodyportion having a lateral end incorporating the first linking portion anda medial end; a second body portion having a medial end incorporatingthe projection and a lateral end engaging the medial end of the firstbody portion; and a locking element for securing the first body portionwith respect to the second body portion; a second member having a secondlinking portion configured and dimensioned to receive at least one ofthe elongate spinal fixation elements, and a cavity having at least oneopening to receive at least a portion of the projection; and a lockingassembly for securing different separation distances between the firstand second elongate spinal fixation elements, the locking assemblyhaving a first end accessible by a user to rotate at least a portion ofthe locking assembly to limit translational travel of the first memberwith respect to the second member, wherein the locking assembly has atleast a first position permitting the first member to slide with respectto the second member, with the first linking portion of the first memberat a user selected angle relative to the second linking portion of thesecond member, and at least a second position preventing translationalmovement of the first member with respect to the second member.
 52. Thetransconnector of claim 51 wherein the medial end of the first bodyportion includes a first textured surface; the lateral end of the secondbody portion includes a second textured surface mating with the firsttextured surface; and the first textured surface is rotatable withrespect to the second textured surface for accommodating convergence ordivergence between the first and second members.
 53. The transconnectorof claim 52 wherein the first and second textured surfaces include astar-grind pattern.
 54. The transconnector of claim 51 wherein thelocking element comprises: a first hole through the medial end of thefirst body portion; a second hole through the lateral end of the secondbody portion aligned with the first hole; and a cap screw insertable inthe first and second holes.
 55. The transconnector of claim 54 whereinthe cap screw has a first end for receiving a tool to turn the cap screwand a second end with a retaining ring for preventing removal of the capscrew from the second hole.
 56. The transconnector of claim 55 whereinthe cap screw has a body with threads and the second hole is threadedfor threadably receiving the cap screw.
 57. The transconnector of claim56 wherein the second hole includes a collar and the retaining ringincludes a resilient member, the resilient member flexing inward uponinsertion of the cap screw through the second hole and flexing outwardonce the resilient member is past the collar for preventing removal ofthe cap screw.
 58. The transconnector of claim 57 wherein the resilientmember includes an end of the cap screw with a lip and a plurality ofslits.
 59. The transconnector of claim 33 wherein the first linkingportion of the first member and the second linking portion of the secondmember each includes a threaded hole and a clamping screw threadablyreceived in the respective threaded hole for securing the first andsecond elongate spinal fixation elements to the first and secondmembers, respectively.
 60. The transconnector of claim 59 wherein eachclamping screw has a first end for receiving a tool to turn the clampingscrew, a threaded cylindrical first body portion, and a conical secondbody portion.
 61. The transconnector of claim 60 wherein the firstlinking portion of the first member and the second linking portion ofthe second member each comprises a tip portion and a curved portionhaving a radius of curvature larger than that of the first and secondelongate spinal fixation elements, respectively.
 62. The transconnectorof claim 61 wherein the first and second elongate spinal fixationelements are clamped between the conical second body portion of eachclamping screw and a region near the tip portion of the first and secondlinking portions, respectively.
 63. A transconnector for coupling firstand second longitudinal spinal rods, the transconnector comprising: afirst member having a first hook portion sized and configured to engagethe first longitudinal spinal rod and a projection associated with thefirst hook portion, the first hook portion having a through holetherein, and the projection having an aperture, the first member furthercomprising a shaft member extending through both the through hole andthe aperture forming an axis of rotation about which the hook portioncan articulate with respect to the projection; a second member having asecond hook portion sized and configured to engage the secondlongitudinal spinal rod and a cavity having at least one opening sizedand configured to receive at least a portion of the projection; and alocking assembly for securing different separation distances and angularorientation between the first and second members, the locking assemblyhaving a first end and a second end, the first end being accessible to auser so that rotation of the first end of the locking assembly causesthe second end of the locking assembly to directly or indirectly engagethe projection; wherein rotation of the first end of the lockingassembly further moves the transconnector from a first position to asecond position, the first position permitting the first member to slideand rotate with respect to the second member, with the first hookportion of the first member at a user selected angle relative to thesecond hook portion of the second member, the second position preventingat least one of translational or rotational movement of the first memberwith respect to the second member.
 64. The transconnector of claim 63wherein rotation of the first end of the locking assembly presses theprojection against the cavity.
 65. The transconnector of claim 63wherein the locking assembly consists of a single screw.
 66. Thetransconnector of claim 63 wherein the locking assembly is operativelyassociated with the projection to limit travel of the first member toprevent uncoupling of the first and second members.
 67. Thetransconnector of claim 63 wherein the projection is an elongated memberhaving an arcuate portion with at least one relatively flat surface andthe flat surface includes a medial wall.
 68. The transconnector of claim67 wherein the projection further includes side edges at the juncture ofthe flat surface and the arcuate portion.
 69. The transconnector ofclaim 68 wherein interaction of the locking assembly and the medial wallprevents uncoupling of the first and second members.
 70. Thetransconnector of claim 69 wherein the side edges limit rotation of theprojection in the cavity.
 71. The transconnector of claim 70 whereininteraction of the locking assembly with the side edges limits rotationof the projection in the cavity.
 72. The transconnector of claim 63wherein the shaft member comprises a threaded screw.
 73. Thetransconnector of claim 63 wherein the shaft member is adjustable tolock the hook portion of the first member with respect to theprojection.
 74. The transconnector of claim 63 wherein the projectioncomprises an edge formed by the junction between the arcuate portion andthe flat surface, the edge and the cavity being sized and configured tolimit angulation of the first member with respect to the second member.75. The transconnector of claim 63 wherein at least a portion of theprojection limits angulation of the first member with respect to thesecond member.
 76. The transconnector of claim 63 wherein the lockingassembly in the second position prevents both translational androtational movement of the first member within respect to the secondmember.
 77. The transconnector of claim 63 wherein the second member hasa threaded opening sized and configured to threadedly receive thelocking assembly.
 78. The transconnector of claim 77 wherein the lockingassembly comprises a set screw that directly or indirectly engages theprojection to substantially prevent movement of the first member withrespect to the second movement.
 79. The transconnector of claim 78wherein the threaded opening has a central axis, the central axis issubstantially perpendicular to the projection.
 80. The transconnector ofclaim 63 wherein the cavity is integrally formed with the hook portionof the second member.
 81. The transconnector of claim 63 wherein thefirst hook portion of the first member is integrally formed with theprojection.
 82. A transconnector for coupling first and secondlongitudinal spinal rods, the transconnector comprising: a first memberhaving a first hook portion sized and configured to engage the firstlongitudinal spinal rod and a projection associated with the first hookportion, the first member comprising: a first body portion having alateral end incorporating the first hook portion of the first member anda medial end; a second body portion having a medial end incorporatingthe projection of the first member and a lateral end engaging the medialend of the first body portion; and a locking element for securing thefirst body portion with respect to the second body portion; a secondmember having a second hook portion sized and configured to engage thesecond longitudinal spinal rod and a cavity having at least one openingsized and configured to receive at least a portion of the projection;and a locking assembly for securing different separation distances andangular orientation between the first and second members, the lockingassembly having a first end and a second end, the first end beingaccessible to a user so that rotation of the first end of the lockingassembly causes the second end of the locking assembly to directly orindirectly engage the projection; wherein rotation of the first end ofthe locking assembly further moves the transconnector from a firstposition to a second position, the first position permitting the firstmember to slide and rotate with respect to the second member, with thefirst hook portion of the first member at a user selected angle relativeto the second hook portion of the second member, the second positionpreventing at least one of translational or rotational movement of thefirst member with respect to the second member.
 83. The transconnectorof claim 82 wherein the medial end of the first body portion includes afirst textured surface; the lateral end of the second body portionincludes a second textured surface mating with the first texturedsurface; and the first textured surface is rotatable with respect to thesecond textured surface for accommodating convergence or divergencebetween the first and second members.
 84. The transconnector of claim 83wherein the first and second textured surfaces include a star-grindpattern.
 85. The transconnector of claim 82 wherein the locking elementcomprises: a first hole through the medial end of the first bodyportion; a second hole through the lateral end of the second bodyportion aligned with the first hole; and a cap screw insertable in thefirst and second holes.
 86. The transconnector of claim 85 wherein thecap screw has a first end for receiving a tool to turn the cap screw anda second end with a retaining ring for preventing removal of the capscrew from the second hole.
 87. The transconnector of claim 86 whereinthe cap screw has a body with threads and the second hole is threadedfor threadably receiving the cap screw.
 88. The transconnector of claim87 wherein the second hole includes a collar and the retaining ringincludes a resilient member, the resilient member flexing inward uponinsertion of the cap screw through the second hole and flexing outwardonce the resilient member is past the collar for preventing removal ofthe cap screw.
 89. The transconnector of claim 88 wherein the resilientmember includes an end of the cap screw with a lip and a plurality ofslits.
 90. The transconnector of claim 63 wherein the first hook portionof the first member and the second hook portion of the second membereach includes a threaded hole and a clamping screw threadably receivedin the respective threaded hole for securing the first and secondlongitudinal rods to the first and second members, respectively.
 91. Thetransconnector of claim 90 wherein each clamping screw has a first endfor receiving a tool to turn the clamping screw, a threaded cylindricalfirst body portion, and a conical second body portion.
 92. Thetransconnector of claim 91 wherein the first hook portion of the firstmember and the second hook portion of the second member each comprises atip portion and a curved portion having a radius of curvature largerthan that of the first and second longitudinal rods, respectively. 93.The transconnector of claim 92 wherein the first and second longitudinalrods are clamped between the conical second body portion of eachclamping screw and a region near the tip portion of the first and secondhook portion, respectively.